1. Field of the Invention
This invention relates to an implement for lopping felled trees, comprising a frame, which is adapted to be suspended from a lifting tackle and is provided with gripping members for engaging a treetrunk from below, with feeding means for imparting a longitudinal movement to the treetrunk and with lopping tools, which are distributed around the periphery of the treetrunk, and is preferably provided with a cross-cutting tool, which is operable to move transversely to the longitudinal feeding direction.
2. Description of the Prior Art.
Such lopping implements are suspended from a suitable lifting tackle consisting in most cases of a crane, which is mounted on a separate chassis, and for a lopping of felled trees are lowered onto the tree which has been felled. As the implement is lowered, the grippers are open and they subsequently engage the treetrunk from below and hold and guide it as it is processed. When the implement has been applied to the treetrunk and has subsequently been raised, the feeding means move the tree past the lopping tools, which have knife edges facing opposite to the feeding direction and which may be secured to separate toolholders or directly to gripper arms of the gripping members. As a result, the tree is lopped throughout the periphery of the treetrunk as the tree is pulled through the implement. A cross-cutting device may optionally be provided for cross-cutting the treetrunk when the tree has been lopped so that felled trees can efficiently be treated.
To pull the tree, when it has been embraced by the grippers, through the lopping tools, a considerable feeding force is required and must be exerted by suitable feeding means. As is apparent from German Patent Specification Nos. 28 11 660 and 28 55 430 or by Published German Patent Application Nos. 37 12 302 and 37 12 303, known feeding means comprise coupling rollers or coupling chains, which are adapted to forcibly engage the treetrunk and are operable to move the felled tree in its longitudinal direction. From U.S. Pat. No. 4,515,192 it is also known that coupling rollers for feeding relatively smooth treetrunks may be movably mounted on the gripping members. But as the tree is fed, the considerable frictional forces between the slide jaws of the gripping members and the treetrunk will often give rise to trouble, particularly if the treetrunk is large in diameter. Such trouble may reside in that the treetrunk becomes stuck in the implement or the feeding means slip on the treetrunk. Such instances will require an interruption of the operation of the implement and will also result in considerable damage to the treetrunks.